Tuesday, 7 May 2013

Mound on Mars Formed by Wind, Not Water

Tue, 05/07/2013 - 7:00am

By Princeton Univ.

The researchers report that air would have flowed up the crater rim (red arrows) and the flanks of Mount Sharp (yellow arrows) in the morning when the Martian surface warmed, and reversed in the cooler late afternoon. The researchers created a computer model showing that the fine dust carried by these winds could accumulate over time to build a mound the size of Mount Sharp even if the ground were bare from the start. The blue arrows indicate the more variable wind patterns on the floor of the crater, which includes the Curiosity landing site (marked by the "x"). Image: NASA, JPL-Caltech, ESA, DLR, FU Berlin, MSSSA roughly 3.5-mile high Martian mound that scientists suspect preserves evidence of a massive lake might actually have formed as a result of the Red Planet's famously dusty atmosphere, an analysis of the mound's features suggests. If correct, the research could dilute expectations that the mound holds evidence of a large body of water, which would have important implications for understanding Mars' past habitability.

Researchers based at Princeton Univ. and the California Institute of Technology suggest that the mound, known as Mount Sharp, most likely emerged as strong winds carried dust and sand into the 96-mile-wide crater in which the mound sits. They report in the journal Geology that air likely rises out of the massive Gale Crater when the Martian surface warms during the day, then sweeps back down its steep walls at night. Though strong along the Gale Crater walls, these "slope winds" would have died down at the crater's center where the fine dust in the air settled and accumulated to eventually form Mount Sharp, which is close in size to Alaska's Mt. McKinley.

This dynamic counters the prevailing theory that Mount Sharp formed from layers of lakebed silt — and could mean that the mound contains less evidence of a past, Earth-like Martian climate than most scientists currently expect.